A tilt rotor aircraft can have wing mounted rotatable nacelles where the nacelles include an engine and rotor hub in a fixed position relative to each other. The nacelles can be selectively rotated between a helicopter mode and an airplane mode. In the helicopter mode, the nacelles can be rotated to an approximate vertical position so that the tilt rotor aircraft can hover similar to a conventional helicopter. In the airplane mode, the nacelles can be rotated to an approximate horizontal position so that the tilt rotor aircraft can fly similar to a fixed wing aircraft. Since the engine rotates along with the rotor hub, the engine must be capable of operating not only in a horizontal orientation, but also a vertical orientation. The ability to operate in a vertical orientation can limit the engine options available for use as well as increasing the certification, testing, and maintenance requirements for the available engines. Further, a rotating engine typically limits maintenance/inspection access around the engine to allow support of the rotating nacelle fairing and firewalls.